As a shaky cease-fire in the east entered its final hours Thursday, thousands of Ukrainians in cars stuffed with belongings lined up at the border to cross into Russia, some vowing never to return.
Many said they were most frightened for their children and desperate to take them to safety.
A commander at the rebel-controlled border post outside the city of Luhansk said 5,000 people had left by evening, joining a stream that he said has continued unabated during the weeklong truce that has failed to end the gunfire and shelling.
Russia says tens of thousands of Ukrainians have come in the 2 1/2 months since Ukraine's government began fighting separatists in the east, a heavily industrial region with a large population of ethnic Russians, many of whom feel strong ties to Moscow.
Air strikes and artillery attacks by the Ukrainian military have infuriated many residents, and many crossing the border on Thursday said they were fleeing the fighting, which has killed more than 400 people since mid-April by the United Nations' estimate.
Those who talked to Associated Press journalists, however, said nothing to indicate that they supported the armed separatists, who have seized government buildings, declared independence and asked Russia to annex the region.
With the cease-fire set to expire on Friday, Ukrainian President Petro Poroshenko called on Russia to support his peace plan "with deeds, not words." He urged Moscow to stop the flow of fighters from Russia.